The Duo name is perfect. It truly is like having two devices in one. The outer device is, by far, the worst iPhone Apple has ever made. It’s a miserable fat little thing. The inner device is a splendid, joyful, beautiful tablet, with a UI that out-iPads the iPad. … The decision of whether you might want to buy a Duo is not easy, because only one of its two selves is good. You might be delighted, despite its clear compromises, if what you value most is a pocketable small tablet and are ambivalent about your iPhone. You might be endlessly frustrated if you love your iPhone, and use it extensively, often for quick interactions throughout the day, every day.
John Gruber has a very long review after using the iPhone Duo for only one week. The takeaway is this: do not buy the Duo if you love the iPhone, buy it if you love the iPad mini.
I would add: buy it only if you have money to burn.











